Bulgaria closed 2025 as a net exporter of electricity, a result that reads well in official summaries and is easy to frame as a sign of system stability. Total electricity production reached 40.1 terawatt-hours, up 5.6% year on year, while domestic consumption increased by 4.9% to 38.7 terawatt-hours, according to data from the Electricity System Operator.
On the surface, the conclusion seems straightforward. Production grew faster than demand, and the difference left the country with a positive export balance of roughly 1.3 terawatt hours, around 32.5% higher than in 2024.
A surplus that looks comfortable, but isn’t wide
The export margin in 2025 was real, but it was not large. It existed because several variables aligned at the same time, not because the system suddenly gained structural breathing space.
Electricity consumption did not weaken during the year. It continued to grow, following economic activity and regional trends. The surplus therefore came entirely from the supply side. That distinction matters more than it might appear, because it shifts attention away from demand dynamics and toward how generation actually behaved.
At this point, the numbers stop being reassured and start becoming conditional.
Production moved faster, but in one direction
The increase in electricity output was not evenly distributed across technologies. Almost all of the additional generation came from one source.
Solar power expanded rapidly during 2025, lifting overall renewable production by around 19%. Photovoltaic installations delivered strong output during favourable periods and reshaped daily generation profiles. This pattern is familiar across Europe, where solar has been growing faster than any other technology, often faster than grids and markets were originally designed to handle.
In Bulgaria, strong solar performance did much of the heavy lifting. Without it, the export balance would have looked very different.
When growth is uneven, stability becomes harder
What tends to get lost behind Solar’s success is what happened elsewhere in the renewable mix. Electricity generation from wind farms declined over the year. Output from biomass facilities also fell. Hydropower production slipped slightly, decreasing by 0.5% to 2.87 terawatt-hours.
Individually, these changes are easy to dismiss. Together, they point to a system where renewable growth is becoming increasingly concentrated rather than diversified. From an operational perspective, that concentration matters. It reduces the system’s ability to self-balance and increases reliance on non-renewable flexibility.
This is where the story becomes less about expansion and more about limits.
Baseload still carries the system
Despite the rise of solar generation, Bulgaria’s electricity system in 2025 remained firmly anchored by baseload capacity. Conventional and nuclear power plants together produced 28.9 terawatt hours, an increase of 1.8% compared to the previous year.
This segment did not grow dramatically, but it did something more important: it kept the system stable when variable generation could not. Evening hours, winter months and periods of low renewable output still depend on dispatchable generation. Without it, exports would not have been possible.
Nuclear output: stable enough, but revealing
Nuclear power continued to play a central role. Total output from the Kozloduy Nuclear Power Plant reached 15.3 terawatt-hours, slightly below the level recorded in 2024. The decline was largely due to unplanned outages at Unit 6, which reduced its annual production to 7.17 terawatt-hours. The system absorbed this reduction without visible stress, that is the positive interpretation.
The other interpretation is more cautious. When a single unit accounts for such a large share of baseload supply, even limited outages shape national figures. In years when solar output is less favourable or regional markets tighten, that sensitivity becomes harder to ignore.
Exports built on alignment, not margin
Looking back at 2025, it becomes clear that Bulgaria’s export surplus was not the result of one decisive factor, but of several conditions aligning at once.
Solar output was strong. Nuclear availability was sufficient, though not flawless. Consumption growth remained manageable. Cross-border markets stayed accessible. None of these elements alone would have guaranteed a surplus. Together, they did.
Change any one of them, and the picture shifts quickly. This is not speculation; it is how tightly balanced systems behave.
What the headline numbers do not capture?
Annual production and consumption figures are useful, but they flatten complexity. They say little about hourly variability, seasonal stress or the system’s ability to absorb shocks.
The 2025 data confirm that Bulgaria can still act as a net exporter under favourable conditions. They do not confirm that this position is structurally secure. The growing dominance of solar generation increases variability. The decline in other renewable sources reduces diversification. Baseload plants remain essential, but their concentration introduces sensitivity. These are not weaknesses yet, they are early signals.
Reading 2025 as a stress test, not a victory lap
There is a temptation to read 2025 as confirmation that the system is performing well. A more useful reading is that the system passed a test, but with limited margin.
The real question is not whether Bulgaria can export electricity in a good year. It is whether the system can remain stable in a less forgiving one, when solar output is weaker, outages last longer or regional markets become less accessible.
